The invention relates in general to coking and in particular to a new and useful method for the volumetric analysis of a furnace charge of predried and preheated coal in a closed system and to a device to implement the method.
Besides the system of chain conveyors which are disposed on the batteries and from which the coal is filled into the furnaces by means of transfer carts or fixed connectors, the use of a hot coal filling cart has proven out well in large industrial facilities for charging horizontal chamber furnaces with preheated coal.
However, special problems crop up when filling hot coal filling carts with preheated coal from the hot coal storage bins because there are some vital differences as compared to filling wet coal filling carts with wet coal from the coal bunkers. First, the filling itself must take place in a closed system to avoid all dust emission and the hazard of fire and explosion. Secondly, preheated coal has a totally different flow behavior from wet coal. Especially due to the addition of considerable amounts of inert gas, the fluidization of preheated coal is intensified.
Now, when using the hot coal filling cart it is necessary to make the closure between the filling containers of the filling cart so flexible that the filling cart can be driven under the storage bins for each charge, and a firm and gastight seal is provided for the duration of the filling operation and that this connection can be broken again subsequently. At the same time, there must be assurance that the amount of coal corresponding to a furnace charge reaches the hot coal filling cart every time.
Hot coal filling carts are known at present where the furnace charge is measured in preweighing bins disposed between the actual hot coal storage bin and the hot coal filling cart (see the publication "Experiences using preheated coal", Technische Mitteilungen, vol. 73, No. 10/80, pages 824-830). Such a coal premeasuring device is described there and is shown in the pictures 3 and 4. Two rows of four premeasuring funnels each are installed there underneath the bunker. Each of these funnels is standing on three pressure pickups by which the respective weight of the furnace charge can be determined. In addition, level indicators and pyrometers are mounted to the upper and lower part of the funnels, by means of which the volume in the funnels is determined. The bucket wheel charging valve between storage bunker and preweighing bins must be shut off as a function of the weight indication and of the level and pyrometer readings when the fill volume is reached. This system, with its great number of preweighing funnels and its weight determination through pressure pickups and volume determination through pyrometers, is very costly and laden with a number of error sources, for instance, when light wind forces can influence the weight determination. Moreoever, due to the interposition of these preweighing bins the actual coal bunker tower must be built about 10 to 12 m higher.